1. Field of the Invention
This invention relates to electrolytic capacitors and more particularly, to non-aqueous liquid electrolytes for aluminum electrolytic capacitors.
2. Description of the Prior Art
Typical electrolytes for electrolytic capacitors are those electrolytes which comprise ionogens dissolved in ethylene glycol. This type of electrolytic capacitor is disadvantageous in relatively poor electrolytic characteristics at low temperatures. In order to overcome the above disadvantage, there has been proposed in Japanese Laid-open patent application No. 54-104559 an electrolyte in which phthalates are dissolved in a mixed solvent of dimethylformamide and ethylene glycol. Japanese Laid-open patent application No. 54-7564 describes an electrolyte which contains amine salts of maleic acid dissolved in a mixed solvent of .gamma.-butyleacetone and ethylene glycol. However, these electrolytes have the respective drawbacks. More particularly, the electrolyte using dimethylformamide is apt to pass through a sealing rubber material and has a short life on drying-up at high temperatures. On the other hand, the solvent mainly composed of .gamma.-butyleacetone is unlikely to pass through a sealing material and is expected to have a long life at high temperatures. However, when there are used solutes which are obtained by neutralizing maleic acid with amines, a high specific conductance cannot be expected.